Notice: For the foreseeable future, the daily reports may
contain
apparent discrepancies between some proposal descriptions
and the listed
instrument usage. This is due to the conversion of
previously approved
ACS WFC or HRC observations into WFPC2, or NICMOS
observations
subsequent to the loss of ACS CCD science capability in
late January.
HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT # 4347
PERIOD COVERED: UT April 23, 2007 (DOY 113)
OBSERVATIONS SCHEDULED
WFPC2 10798
Dark Halos and Substructure from Arcs & Einstein Rings
The surface brightness distribution of extended
gravitationally lensed
arcs and Einstein rings contains super-resolved
information about the
lensed object, and, more excitingly, about the smooth and
clumpy mass
distribution of the lens galaxies. The source and lens
information can
non-parametrically be separated, resulting in a direct
"gravitational
image" of the inner mass-distribution of
cosmologically-distant galaxies
{Koopmans 2005; Koopmans et al. 2006 [astro-ph/0601628]}.
With this goal
in mind, we propose deep HST ACS-F555W/F814W and
NICMOS-F160W WFC
imaging of 20 new gravitational-lens systems with
spatially resolved
lensed sources, of the 35 new lens systems discovered by
the Sloan Lens
ACS Survey {Bolton et al. 2005} so far, 15 of which are
being imaged in
Cycle-14. Each system has been selected from the SDSS and
confirmed in
two time- efficient HST-ACS snapshot programs {cycle
13&14}.
High-fidelity multi-color HST images are required {not
delivered by the
420s snapshots} to isolate these lensed images {properly
cleaned,
dithered and extinction-corrected} from the lens galaxy
surface
brightness distribution, and apply our "gravitational
maging" technique.
Our sample of 35 early-type lens galaxies to date is by
far the largest,
still growing, and most uniformly selected. This minimizes
selection
biases and small-number statistics, compared to smaller,
often
serendipitously discovered, samples. Moreover, using the
WFC provides
information on the field around the lens, higher S/N and a
better
understood PSF, compared with the HRC, and one retains
high spatial
resolution through drizzling. The sample of galaxy mass
distributions -
determined through this method from the arcs and Einstein
ring HST
images - will be studied to: {i} measure the smooth mass
distribution of
the lens galaxies {dark and luminous mass are separated
using the HST
images and the stellar M/L values derived from a joint
stellar-dynamical
analysis of each system}; {ii} quantify statistically and
individually
the incidence of mass-substructure {with or without
obvious luminous
counter- parts such as dwarf galaxies}. Since dark-matter
substructure
could be more prevalent at higher redshift, both results
provide a
direct test of this prediction of the CDM hierarchical
structure-formation model.
ACS/SBC 10815
The Blue Hook Populations of Massive Globular Clusters
Blue hook stars are a class of hot {~35,000 K} subluminous
horizontal
branch stars that have been recently discovered using HST
ultraviolet
images of the globular clusters omega Cen and NGC 2808.
These stars
occupy a region of the HR diagram that is unexplained by
canonical
stellar evolution theory. Using new theoretical
evolutionary and
atmospheric models, we have shown that the blue hook stars
are very
likely the progeny of stars that undergo extensive
internal mixing
during a late helium core flash on the white dwarf cooling
curve. This
"flash mixing" produces an enormous enhancement
of the surface helium
and carbon abundances, which suppresses the flux in the
far ultraviolet.
Although flash mixing is more likely to occur in stars
that are born
with high helium abundances, a high helium abundance, by
itself, does
not explain the presence of a blue hook population - flash
mixing of the
envelope is required. We propose ACS ultraviolet
{SBC/F150LP}
observations of the five additional globular clusters for
which the
presence of blue hook stars is suspected from longer
wavelength
observations. Like omega Cen and NGC 2808, these five
targets are also
among the most massive globular clusters, because less
massive clusters
show no evidence for blue hook stars. Because our targets
span 1.5 dex
in metallicity, we will be able to test our prediction that
flash-mixing
should be less drastic in metal-rich blue hook stars. In
addition, our
observations will test the hypothesis that blue hook stars
only form in
globular clusters massive enough to retain the
helium-enriched ejecta
from the first stellar generation. If this hypothesis is
correct, then
our observations will yield important constraints on the
chemical
evolution and early formation history in globular
clusters, as well as
the role of helium self-enrichment in producing blue
horizontal
branch morphologies and multiple main sequence turnoffs.
Finally, our
observations will provide new insight into the formation
of the hottest
horizontal branch stars, with implications for the origin
of the hot
helium-rich subdwarfs in the Galactic field.
WFPC2 11024
WFPC2 CYCLE 15 INTERNAL MONITOR
This calibration proposal is the Cycle 15 routine internal
monitor for
WFPC2, to be run weekly to monitor the health of the
cameras. A variety
of internal exposures are obtained in order to provide a
monitor of the
integrity of the CCD camera electronics in both bays {both
gain 7 and
gain 15 -- to test stability of gains and bias levels}, a
test for
quantum efficiency in the CCDs, and a monitor for possible
buildup of
contaminants on the CCD windows. These also provide raw
data for
generating annual super-bias reference files for the
calibration
pipeline.
FGS 11019
Monitoring FGS1r's Interferometric Response as a Function
of Spectral
Color
This proosal uses FGS1r in Transfer mode to observe
standard single
stars of a variety of spectral types to obtain point
source
interferograms for the Transfer mode calibration library.
In specific
cases, the calibration star will also be observed in POS
mode multiple
times with the F583W and F5ND elements to provide the data
to verify the
stabiligy of the cross filter calibration.
NIC1/NIC2/NIC3 8794
NICMOS Post-SAA calibration - CR Persistence Part 5
A new procedure proposed to alleviate the CR-persistence
problem of
NICMOS. Dark frames will be obtained immediately upon
exiting the SAA
contour 23, and every time a NICMOS exposure is scheduled
within 50
minutes of coming out of the SAA. The darks will be
obtained in parallel
in all three NICMOS Cameras. The POST-SAA darks will be
non- standard
reference files available to users with a USEAFTER
date/time mark. The
keyword 'USEAFTER=date/time' will also be added to the
header of each
POST-SAA DARK frame. The keyword must be populated with
the time, in
addition to the date, because HST crosses the SAA ~8 times
per day so
each POST-SAA DARK will need to have the appropriate time
specified, for
users to identify the ones they need. Both the raw and
processed images
will be archived as POST-SAA DARKSs. Generally we expect
that all NICMOS
science/calibration observations started within 50 minutes
of leaving an
SAA will need such maps to remove the CR persistence from
the science
images. Each observation will need its own CRMAP, as
different SAA
passages leave different imprints on the NICMOS detectors.
WFPC2 10884
The Dynamical Structure of Ellipticals in the Coma and
Abell 262
Clusters
We propose to obtain images of 13 relatively luminous
early type
galaxies in the Coma cluster and Abell 262 for which we
have already
collected ground based major and minor axis spectra and
images. The
higher resolution HST images will enable us to study the
central regions
of these galaxies which is crucial to our dynamical
modelling. The
complete data set will allow us to perform a full
dynamical analysis and
to derive the dark matter content and distribution, the
stellar orbital
structure, and the stellar population properties of these
objects,
probing the predictions of galaxy formation models. The
dynamical
analysis will be performed using an up-to-date axi-symmetric
orbit
superposition code.
WFPC2 11023
WFPC2 CYCLE 15 Standard Darks - part 1
This dark calibration program obtains dark frames every
week in order to
provide data for the ongoing calibration of the CCD dark
current rate,
and to monitor and characterize the evolution of hot
pixels. Over an
extended period these data will also provide a monitor of
radiation
damage to the CCDs.
WFPC2 11032
CTE Extended Targets Closeout
Measuring the charge transfer efficiency {CTE} of an
astronomical CCD
camera is crucial to determining the CCD's photometric
fidelity across
the field of view. WFPC2's CTE has degraded steadily over
the last 13
years because of continuous exposure to trapped particles
in HST's
radiation environment. The fraction of photometric signal
lost from
WFPC2's CTI {change transfer inefficiency} is a function
of WFPC2's time
in orbit, the integrated signal in the image, the location
of the image
on the CCD, and the background signal. Routine monitoring
of WFPC2's
degrading CTE over the last 13 years has primarily
concerned the effects
of CTI on point-source photometry. However, most of the
sources imaged
by WFPC2 are extended rather than point-like. This program
aims to
characterize the effects of CTI on the photometry and
morphology of
extended sources near the end of WFPC2's functional life.
Images of a
standard field within the rich galaxy cluster Abell 1689
are recorded
with each WFPC2 camera using the F606W and F814W filters.
These images
will be compared with contemporaneous images of Abell 1689
recorded with
the field rotated by approximately 180 degrees to assess
differences
between extended sources imaged near and far from the
serial register.
The images will also be compared with similar images
recorded in Cycle 8
{Program 8456} to characterize the rate of CTE degradation
over the
lifetime of WFPC2.
WFPC2 11083
The Structure, Formation and Evolution of Galactic Cores
and Nuclei
A surprising result has emerged from the ACS Virgo Cluster
Survey
{ACSVCS}, a program to obtain ACS/WFC gz imaging for a
large, unbiased
sample of 100 early-type galaxies in the Virgo Cluster. On
subarcsecond
scales {i.e., <0.1"-1"}, the HST brightness
profiles vary systematically
from the brightest giants {which have nearly constant
surface brightness
cores} to the faintest dwarfs {which have compact stellar
nuclei}.
Remarkably, the fraction of galaxy mass contributed by the
nuclei in the
faint galaxies is identical to that contributed by
supermassive black
holes in the bright galaxies {0.2%}. These findings
strongly suggest
that a single mechanism is responsible for both types of
Central Massive
Object: most likely internally or externally modulated gas
inflows that
feed central black holes or lead to the formation of
"nuclear star
clusters". Understanding the history of gas
accretion, star formation
and chemical enrichment on subarcsecond scales has thus
emerged as the
single most pressing question in the study of nearby
galactic nuclei,
either active or quiescent. We propose an ambitious HST
program {199
orbits} that constitutes the next, obvious step forward:
high-resolution, ultraviolet {WFPC2/F255W} and infrared
{NIC1/F160W}
imaging for the complete ACSVCS sample. By capitalizing on
HST's unique
ability to provide high-resolution images with a sharp and
stable PSF at
UV and IR wavelengths, we will leverage the existing
optical HST data to
obtain the most complete picture currently possible for
the history of
star formation and chemical enrichment on these small
scales. Equally
important, this program will lead to a significant
improvement in the
measured structural parameters and density distributions
for the stellar
nuclei and the underlying galaxies, and provide a
sensitive measure of
"frosting" by young stars in the galaxy cores.
By virtue of its superb
image quality and stable PSF, NICMOS is the sole
instrument capable of
the IR observations proposed here. In the case of the
WFPC2
observations, high-resolution UV imaging {< 0.1"}
is a capability unique
to HST, yet one that could be lost at any any time.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS: (None)
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS GSacq
11
11
FGS REacq
04
04
OBAD with Maneuver 25
25
SIGNIFICANT EVENTS:
Evaluation of Universal Kalman Filter performance
continued. Multiple text
segments were executed, all of them successfully.
Details follow.
The Kalman Filter was restarted at 113/13:17 (OR 18046-0)
during orbit
day and during an M2G guiding interval. The filter was
activated with
the MSS, CSS and Gyro-1 sensor inputs enabled. All UKF parameters
showed
nominal convergence and steady-state operation. The test
was an
MSS/CSS/Gyro-1 Initialization Test Case with the
spacecraft inertially
fixed during a fast changing B-field in orbit day
(MC_G1_INF, Test #17).
The KF was halted at 14:10 and reconfigured back to the
default MSS/CSS
configuration.
The Gyro-1 sensor input was added to the KF at 113/15:00
(OR 18047-0)
during orbit day and during a T2G guiding interval. The
filter was
running with the MSS and CSS sensor inputs enabled and
converged. All
UKF parameters showed nominal operation. The test was an
MSS/CSS Test
Case with the Gyro-1 sensor input added to an already
converged filter.
The spacecraft was inertially fixed during a fast changing
B-field in
orbit day (MC_G1_RNF, Test #29). The Gyro-1 input was
removed at 16:10
during an F2G period in orbit day to reconfigure the KF
back to default
MSS/CSS configuration.
The Kalman Filter was restarted at 113/18:44 (OR 18045-0)
just prior to
orbit night entry (approx. 1 minute) and during an F2G
guiding interval
and with the spacecraft inertially fixed (M_C_INP, Test
#10). The filter
was activated with the default configuration of MSS and
CSS sensor
inputs enabled. The test was executed to monitor the
initial nominal
convergence of the filter as it crossed the EON penumbra.
The filter
began to converge initially, paused and two minutes after
EON it
continued toward convergence. All UKF parameters showed
nominal
steady-state operation.
The Kalman Filter was restarted at 113/20:01 (OR 18046-0)
during orbit
day and during an M2G guiding interval. The filter was
activated with
the MSS, CSS and Gyro-1 sensor inputs enabled. All UKF
parameters showed
nominal convergence and steady-state operation. The test
was an
MSS/CSS/Gyro-1 Initialization Test Case with the
spacecraft inertially
fixed during a slow changing B-field in orbit day
(M_G1_INS, Test #18).
The KF was halted at 20:35 and reconfigured back to the
default MSS/CSS
configuration.
The Gyro-1 sensor input was added to the KF at 113/21:46
(OR 18047-0)
during orbit day and during a M2G guiding interval. The
filter was
running with the MSS and CSS sensor inputs enabled and
converged. All
UKF parameters showed nominal operation. The test was an
MSS/CSS Test
Case with the Gyro-1 sensor input added to an already
converged filter.
The spacecraft was inertially fixed during a slow changing
B-field in
orbit day (M_G1_RNS, Test #30). The KF was halted at 23:20
and
reconfigured back to the default MSS/CSS configuration.
The Kalman Filter was restarted at 113/23:34 (OR 18045-0)
during orbit
night and during an T2G guiding interval. The filter was
activated with
the MSS and CSS sensor inputs enabled. The KF was
restarted as the
OBAD-1 correction maneuver was occurring and all the UKF
parameters
showed nominal convergence and steady-state operation. The
test was an
MSS/CSS Initialization Test Case with the spacecraft
inertially fixed
during a slow changing B-field in orbit night (M_0_INS,
Test #4). The
test may be re-executed as the intent was to execute with
the spacecraft
inertially fixed.
The Gyro-1 sensor input was added to the KF at 113/23:55
(OR 18048-2)
during orbit night and during an F2G guiding interval. The
filter was
running with the MSS and CSS sensor inputs enabled and
converged. The
Gyro-1 sensor input was later removed at 114/01:18 to
monitor the
response of the filter when the gyro input is removed
during orbit night
with a slow changing B-field and no vehicle maneuver
occurring
(M_G1_HNS, Test #26). All UKF parameters showed nominal
operation.
The test above completed testing for the day and left the
KF configured
in the default MSS/CSS mode